This invention relates to the detection of insoluble (solubility less than 0.1 percent) pollutants that sink in water, and more particularly to the method and apparatus for locating and mapping pools of a pollutant in a body of water.
Spills or releases of hazardous materials into waterways and lakes cause severe environmental impact that could result in massive fish kills or contamination of municipal water supplies. Many of these hazardous materials are immiscible and denser than water. This class of pollutants may sink rapidly to the bottom of a still body of water forming localized pools. If turbulence is present, as in a river, they will remain suspended in the water until they reach a quiescent area of the watercourse where they may settle into a pool along the bottom. A pollutant mapping technique is needed to locate the hazardous material and direct rapid cleanup operations to minimize widespread biological and environmental impact.
Of all forms of energy which may be considered for scanning a body of water in search of pools of pollutants, sound is the most promising because it travels through water the best. In turbid, muddy water conditions, radiation (both light and radio waves) are attenuated to a far greater degree than is sound. Because of its relative ease of propogation, ultrasonic sound systems are used for depth sounding, fish finding, environmental monitoring, biomedical research, and metallurgy applications, as well as exploration of seas, rivers, and lakes. Ultrasonics and more particularly catacoustics (reflected sounds) form the framework for the pollutant mapping technique of the present invention.